Operation of computer systems and other electronic devices may generate electromagnetic fields (EM fields) in the radio frequency (RF) spectrum. These energies, referred to as electromagnetic interference (EMI) may cause “noise” or otherwise degrade performance of other computer systems and electronic devices. Accordingly, computer systems and other electronic devices may be shielded to reduce emissions which cause EMI and disrupt the operation of other equipment. Computer systems and electronic devices may also be shielded against EMI caused by other equipment in order to function properly in the intended environment.
Filters have been developed to reduce emissions that cause EMI. However, EMI filters may require modifying the circuitry, can be expensive, and do not protect against EMI caused by other computer systems or electronic devices. Alternatively, shielding may be used to reduce emissions that cause EMI. Shielding may be accomplished by enclosing circuits or other sources of EMI. Shielding also protects against EMI caused by other computer systems or electronic devices.
EMI shielding may be accomplished by sealing openings in enclosure with foam gaskets. These foam gaskets work well if the mating surfaces of the enclosure are highly conductive (e.g., metal). However, the materials used for these enclosures may include zinc or other heavy metals, and therefore may be insulated to comply with Reduction of Hazardous Substances (RoHS) standards. Obviously, foam gaskets cannot pierce this insulating layer, thereby reducing its effectiveness for EMI shielding.
Although a metal gasket may be used to pierce the insulating layer, metal gaskets typically requires relatively high compressive forces in order to pierce the insulating layer. Accordingly, the enclosure has to be designed to resist these forces. Such a design increases manufacturing costs and the size/weight of the final product, all of which are undesirable in electronic devices.